Means and methods of abrading



April 29, 1947. c. A. ELLIS YETAL 2,419,543

MEANS AND METHODS OF ABRADING Filed Sept. 4, 1944 2 Sheets-Sheet 1 w ti1-- 8 38 0' 5 INVENTOR.

April 29, 1947- c. A. ELLIS arm. 2,419,543

MEANS AND METHODS OF ABRADING El led Sept. 4, 1944 1 2 Sheets-Sheet 2 I\NVENTOR CHBRLES H. ELL/S LHMQENCE A. SEVERY BY 86/ M;

ATTORN Y Patented Apr. 29, 1947 MEANS AND METHODS OF ABRADING Charles A.Ellis and Lawrence A. Severy, Southbridge, Mass., assignors to AmericanOptical Company, Southbridge, Mass., a voluntary association ofMassachusetts Application September 4, 1944, Serial No. 552,604

15 Claims.

This invention relates to curve generating means and has particularreference to novel means for obtaining surfaces of compound curvaturesand methods of obtaining the same.

One of the principal objects of the invention is to provide novel meansand methods of obtaining surfaces of compound curvatures such as areembodied in producing ophthalmic lenses commercially known in the art astoric lenses.

Another object is to provide curve generating means which will enableindependently controllable curves to be simultaneously formed in the twomajor meridians of a lens.

Another object is to provide means for ontrolling the depth of grindingof compound surfaces of the character described.

Another object is to provide novel means and methods of controlling thecurves in the major meridians of an ophthalmic lens whereby the curvesare generated by a cupped grinding tool and the curvatures of said majormeridians, which may be plus, or minus, or even plus and minuscurvatures, are controlled by the angular relation of the tool withrespect to the surface of the blank in said two major meridians.

Another object is to provide means in an apparatus of the characterdescribed whereby the angle of the tool may be synchronously shiftedfrom one major position of ,movement to another during the abrading incombination with means for altering said majorpositions of movement.

Another object is to provide a novel method of producing compoundsurface curvatures on an article.

Other objects and advantages of the invention will become apparent fromthe following description taken in connection with the accompanyingdrawings and it will be apparent that many changes may be made in thedetails of construction, arrangement of parts and steps of the processesor methods shown and described without departing from the spirit of theinvention as expressed in the accompanying claims. We, therefore, do notwish to be limited to the exact details of construction, arrangement ofparts and methods shown and described as the preferred form only hasbeen given by way of illustration.

Referring to the drawings:

Fig. 1 is a diagrammatic side elevational view of the device embodyingthe invention;

Fig. 2 is a face view of the abrading tool embodying the invention;

Fig. 3 is a perspective view of a blank having the resultant surfacecurvatures generated thereon according to the present invention;

Fig. 4A and Fig. 4B are cross sectional views taken along the majormeridians of a blank having resultant plus or convex surface curvaturesgenerated thereon;

Fig. 5A and Fig. 5B are cross sectional views of a blank havingresultant minus and plus surface curvatures respectively generatedthereon;

Fig. 6A and Fig. 6B are cross sectional views of a blank havingresultant concave or minus surface curvatures generated thereon;

Fig. 7 is a side elevational view of a portion of Fig. l, somewhatenlarged and with certain parts thereof broken away to show the pivotalmounting for the abrading tool; and

Figs. 8A, 8B and 8C are diagrammatic views; showing in Fig. 8A the toolin its neutral position, in Fig. 8B the tool in an angled position forgenerating a convex surface curvature and in Fig. the tool in anotherangled position for generating a concave surface curvature.

Referring more particularly to the drawings wherein like characters ofreference designate like parts throughout the several views, the deviceembodying the invention comprises a spindle 4 on which a lens holder 5is supported. A lens blank 6 is preferably secured to the lens holder 5by a suitable layer of pitch or other adhesive I. The spindle 4 isreciprocally supported internally of a bearing 8 whereby the said lensholder and blank 6 may be raised or lowered with the uppermost positionof movement thereof determined by a suitable scale 9 and indicator Ill.The indicator I0 is carried by an adjustable stop Ill. A lever llpivotally supported at I2 is adapted to engage the lower end of thespindle 4 and to raise said spindle under the action of a weight I2 hungfrom the opposed end of the lever. The movement of the lever is limitedby the adjustable stop ID.

The spindle 4 is provided with a suitable pulley or the like Il'connected through a belt I2 to a pulley l3. The pulley I3 is mounted ona shaft l4 rotated by a suitable reduction gearing l5 through a motorI6. A gear I! carried by the spindle 4 is connected through a suitableidler gear l8 to a gear 19 carried by a spindle 20. The spindle 20 has adisc 2| pivotally connected thereto as illustrated at 22 whereby thesaid disc 2| may be angularly adjusted, the said angling being broughtabout by a link 23 pivotally connected at 24 to said disc 2| andpivotally connected to a sleeve 25 reciprocally mounted on the spindle20. The sleeve 25 is adjusted longitudinally of the spindle 20 by meansof a yoke 59 carried by the slide member 26. The slide 26 is carried bya fixed wall member 21 and is locked in adjusted position by a clamp 28.The slide 26 is provided with an indicator 29 cooperatively functioningwith a scale 30 for determining the position of adjustment of the sleeve25. Movement of the sleeve 25 longitudinally of the spindle 20, actingthrough the link 23, causes the disc 2| to be adjusted to a given fixedangular position. The disc 2| is of a size and controlled in detailhereinafter.

contour, the functions of which will be described However, it should behere noted that preferred forms of the disc 2| would include circularand elliptical contours of suitable sizes to give adequate amounts ofangling to the shaft 32 and thus to the tool 3| for the curvature orcurvatures to be generated.

A ring or cupped grinding tool 3| is mounted on a shaft 32 rotatablysupported in spaced bearings 33 and 34 carried by a bracket 35. Thebracket 35 is pivotally connected at 36 to a suitable support 36' withthe said center line of the pivot 36 being coaxial with the center ofthe cross sectional curvature of the abrading surface of the cup or ringtool 3| and with the said center line of the pivot intersecting thelongitudinal axis of the spindle 4. The shaft 32 is provided with apulley 31 adjacent the upper end thereof which is'connected through asuitable belt 38 to a pulley 39 driven by the motor IS.

The bracket 35 is connected at 35 to a link 40 which has its oppositeend pivotally connected at 40' to an intermediate part of a lever 4|slideably supported in a bearing 42. The bearing 42 is in turn pivotallyconnected to a bracket 43 carried by a slide member 44. The slide member44 is slideably supported in a wall 45 and is locked in adjustedposition by means of a clamp screw or the like 46. The bearing 42 isprovided with an indicator 4! which functions cooperatively with asuitable scale 48 for controlling the position of adjustment of thebearing 42. The lever 4| is adapted to oscillate about the center 48 ofthe pivotal connection of the bearing 42 with the bracket 43. Bymovement of said bearing longitudinally of the lever 4| the effectivelength through which the lever 4| acts may be varied. The lever 4|,adjacent the rear end thereof, is pivotally connected at 49 to-a sliderod 50 slideably supported in a bearing The slide rod 50 is providedwith a contact member 52 adapted to engage the periphery of the disc 2|and is held in engagement with said disc 2| by a spring or the like 53.

It is to be noted that the spindle 4 is provided with a spline portion54 which will permit the said spindle to be moved longitudinally throughthe bearing 8, the pulley H and the gear I! while retaining said pulleyand gear in interlocked driving relation therewith.

The abrading tool 3| as shown in Fig. 2 is of a circular shapepreferably having its abrading surface impregnated with diamondparticles or other suitable abrasive means with the said abradingsurface being of circular cross sectional contour whereby the said toolmay be moved to diiferent angular relations. with the lens blank withoutchanging the positional relation of said tool with said blank. Thiscauses a difierent abrading portion of the tool to be engaged with theblank at diiferent angular adjustments of said tool.

The curve generating principle of such an abrading tool is commonlyknown in the art of spherical surface generation with the diameter ofthe tool and its angle with respect to the rotational axis of the blankbeing the controlling factors as to the curve generated.

Referring more particularly to the operation of the device the curve tobe generated in one of the major meridians of the blank, for example,curve A, as indicated in Fig. 3, is controlled by angling the tool 3| tothe left about the pivot 36 and with respect to the axis of rotation ofthe blank 5 by the rotation of the disc 2| to the posi- 4 tion indicatedby Fig. 1. The maximum angle of the tool 3| to the left is at such timedetermined by the angular adjustment of the disc 2| relative to shaft 20and the adjustment of bearing 42, that is, when the lever 4| reaches itsextreme position of throw in the direction of the arrow 55. the tool 3|will be angled to a position to generate a curvature along meridian A.This produces the curve desired in one of the major meridians of theblank. The curve in the opposed major meridian B, as indicated in Fig.3, is controlled by the maximum position of movement of the lever 4| inthe opposite direction, that is, in the direction of the arrow 56 asbrought about by the angling of the disc 2| through degrees.

It is first pointed out that he scale 48 and indicator 41 will enablethe operator to determine the position at which the bearing 42 must beset to obtain the effective lever arm length desired between the points48' and 49; The scale 30 and indicator 29 will enable the operator todetermine the set angle of the disc 2|.

Let us assume, for example, that the disc 2| is of circular shape andwhen angled, as indicated in Fig. 1 and as described above, the extentof ratio of movement of the lever 4| in the directions 55 or 55 will becontrolled by the extent of said angling of the tool 3| and by thediameter of the disc 2|. This ratio is such as to tilt the tool 3| tothe maximum positions required to produce the curves desired in the twomajor meridians of the lens. This gives the maximum throw of the lever4| or anglin of the tool in said respective meridians A and B. In thedevice as shown the initial angling of the tool at the maximum movementof the lever 4| in the direction 56 is controlled by adjustment of thesleeve 42 longitudinally of the lever 4| and this provides means wherebythe base curve B may be varied according to the prescriptiverequirements and will produce a concave surface or negative curvature onthe blank 6. The ratio of difference between curves A and B iscontrolled by the angling of the disc 2| to allow movement of the tool3| in the opposite direction 55 and since in the adjustment shown forthe disc 2| the tool 3| pivots only as far as its neutral position nocurvature in the meridian A will be produced. However, should the disc2| be adjusted to a slightly greater angle relative to the shaft 20,movement of the tool to the left of the neutral position would occur anda convex surface curvature would be produced on the meridian A. On theother hand, if disc 2| is angularly adjusted in the opposite directionsomewhat from the position shown in Fig. 1, the tool 3| in its tiltingmovement toward the left will only reach a point to the right of theneutral position and thus a concave surface curvature will result in themeridian A.

Should a disc of smaller diameter'be used at 2| and the device adjustedso as to allow all of the tilting action of the tool 3| under theinfluence of this disc to take place to the left of said neutralposition convex surface curvatures will be produced on the majormeridians A and B. Thus a lens blank having two different convexcurvatures as shown by Figs. 4A and 4B respectively, or a lens having a.concave curvature and a convex curvature as shown by Figs. 5A and 5B, ora lens having two concave curvatures-as shown by Figs. 6A and 63 'may beproduced.

It has been stated above that the disc 2| has been assumed to becircular in contour. The contour shape, however, of said disc may bevaried as desired to bring about a difierent rate of change between thepower of the curves A and B. For example, it may be desired to form saiddisc to an elliptical shape.

During the curve generating of the device the blank 6 is continuouslyrotated about the axis of the spindle 4 and the ring or cupped tool 3|is likewise continuously rotated preferably at a higher rate of speed.The related speeds are controlled by the reduction gearing l5. As thering or cupped tool 3| is rotated the spind e 20 is simultaneouslyrotated thereby causing the disc 2| to rotate and, through itsengagement with the contact member 52, will simultaneously cause thelever 4| to be swung about the pivot 48'. By reason of the fact that thelever 4| is connected through the link 40, with the bracket 35supporting the tool spindle, the angle of the p e 32 will be changed andcaused to move from one extreme angle in the direction of the arrow 55to the extreme angle in the direction of e arrow 56 with the relatedspeed of rotation' of the blank 6 being so controlled that the maximumtilt in one direction will occur in one of the jor meridians of theblank and the maximum ti Qin the other direction will occur in the othermajor meridian. This swinging movement of the lever:

4| will cause the bracket 35 to be angled about the center of its pivot36 thereby changing the angular relation of the tool with respect to theblank during the abrading.

Any slack which may be introduced in the belt 38 durin the angularmovement of the bracket 35 can be taken up by a suitable idler pulley 51pivotally supported at 58 and held in engagement with the belt throughthe provision of a suitable spring or weight (not shown) tending toconstantly urge the pulley 51 toward the belt. It will be seen,therefore, that when the point on the disc 2| nearest the axis ofrotation of the spindle 20 engages the member 52, the bracket 35 will beat its maximum angle in the direction of the arrow 55; and when thehighest point on the disc 2| is in engagement with the member 52, thebracket will be moved to its maximum angle in the direction of the arrow56 thereby causing the tool 3| to generate the desired curvatures in themeridians A and B of the lens. This movement from one major position tothe other is brought about by a synchronous action so that a toric curveis generated on the surface of the blank. By controlling the stopposition of the lever through the scale 9 and indicator ID, the extentof the material removed from the blank may be controlled.

From the foregoing description it will be seen that simple, efficientand economical means and method have been provided for accomplishing allof the objects and advantages of the invention.

Having described our invention, we claim:

1. A device of the character described comprisin a cupped type abradingtool and a holder for supporting a lens blank thereon for associationwith said tool, means for supporting said tool for rotation and fortilting movement about a fixed axis relative to the blank, means for establishing the range of tilt of said tool and for moving said tool fromone maximum angular position to another, means for varying said range oftilt, means for rotating said holder to rotate said blank and means forcausing said blank and tool to move toward each other during saidabrading, the means for causing rotation of the holder and the means forcausing angular movement of the tool being so interconnected that themaximum angle of movement of the tool in one direction will take placein one meridian of the blank and the maximum angle of movement of thetool in the other direction will take place in another meridian of theblank to thereby form a toric lens surface.

2. In a device of the character described a cupped abrading toolsupported for tilting movement about a given fixed center, variablemeans for controlling the range of tilt of said tool from one maximumposition to another, means for engaging a lens blank with said tool,means for rotating said tool, means for rotating said engaging means,the means for causing rotation of said engaging means and the means forcausing angling of said tool from one maximum position to the otherbeing so re ated that the tool will be angled to its maximum position oftilt in one direction when one major meridian of the blank is engaged bythe tool and will be angled to its maximum position of tilt in theopposite direction when the other major meridian of the blank is engagedby the tool.

3. In a device of the character described the combination of a cuppedtool supported for tilting movement about a given fixed center, saidtool having a curved abrading surface throughout one edge thereof withits center located at the center of tilt, means for supporting a lensblank for movement toward and away from said abrading tool along anaxial line intersecting the axis of the center of tilt of the tool,means for tilting said tool from one major position to another, meansfor rotating said tool and means for rotating said blank supportingmeans, the means for causing rotation of said blank supporting means andthe means for causing tilting of said tool bein so related that themaximum tilting in one direction will occur at one major meridian of theblank and the maximum tilting in the opposite direction will occur atthe other major meridian of the blank.

4. In adevice of the character described the combination of a cuppedtool supported for tilting movement about a given fixed center, saidtool havinga curved abrading surface throughout one edge thereof withits center located substantially concentric with the center of tilt,means for supporting a lens blank for movement toward and away from saidahrading tool along an. axial line intersecting the axis of the centerof tilt, means for tilting said tool from one extreme position toanother, means for rotating said tool and means for rotating said blanksupporting means, the means for causin rotation of said blank supportingmeans being so related with respect to the means for causing tilting ofsaid tool that the maximum tilting in one direction will occur at onemajor meridian of the blank and the maximum tilting in the oppositedirection will occur at the other major meridian of the blank, and meansfor altering the extent of tilt in said opposite directions.

5. In a device of the character described the combination of a cuppedtool supported for tilting movement about a given fixed center, saidtool having a curved abrading surface throughout one edge thereof withits center located substantially concentric with the center of tilt,means for supporting a lens blank for movement toward and away from saidabrading tool along an exial line intersecting the axis of the center oftilt, means for tilting said tool from one major position to another,means for rotating said tool and means for rotating said blanksupportingmeans, the means for causing rotation of said blank supportingmeans being so related with and interconnected to the means for causingtilting of said tool that the maximum tilting in one direction willoccur at one major meridian of the blank and the maximum tilting in theopposite direction will occur in the other major meridian or the blank,and means for altering the range of tilt.

6. In a device of the character described the combination of a bracketpivoted adjacent one end thereof for tilting'about a given center, acupped tool rotatably supported by said bracket, said cupped tool havinga curved abrading surface in the direction of a section of said toolwith the center of said curve substantially coaxial with the axis of thepivot of the bracket, means for supporting a' lens blank for movementtoward and away from said tool about a longitudinal axis intersectingthe axis of said pivot, means for rotating said blank supporting means,a lever supported for movement about a pivot, means for varying theposition of said lever pivot, said lever being connected with .thebracket through a link member, a contact member carried by said lever, adisk-like member engaging said contact member, means for angling saiddisk to variably set positions, means for rotating said disk, means forretaining said contact member in engage ment with said disk and meansfor controlling the extent of movement of said blank toward saidabrading tool during the abrading operation.

'7. In a device of the character described the combination of a bracketpivoted adjacent one end thereof for tilting about a given center, acupped tool rotatably supported by said bracket, said cupped tool havinga curved abrading surface in the direction of a section of said toolwith the center of said curve substantially coaxial with the axis of thepivot of the bracket, means for supporting a lens blank for movementto-o ward and away from said tool about a longitudinal axis intersectingthe axis of said pivot, means for rotating said blank supporting means,a lever supported for movement about a pivot, means for varying theposition of said lever pivot, said lever being connected with thebracket through a link member, a contact member carried by said lever,

a disk-like member engaging said contact member, means for angling saiddisk to variably set positions, means for rotating said disk, means forretaining saidcontact member in engagement with said disk and means forcontrolling the extent of movement of said blank toward said abradingtool during the abrading operation, the rotation of said blanksupporting means and of said disk being so related as to cause thecupped tool to'assume a given angular relation with theblank at onemajor meridian thereof and to cause said cupped tool to assume a givendiflerent angular relation with said blank at another major meridianthereof.

8. The method of generating compound surface curvatures on an articlecomprising rotating said article about a first axis and while inengagement with a rotating cup-like abrading tool, angling said toolabout a second fixed axis normal to and intersecting said first axis totwo given angular positions with respect to the article during therotation thereof, and causing the article to rotate in such a mannerthat the tool will assume one of its angular positions in one of themajor meridians of the article and will assume its other angularposition in another major meridian of the article as said tool andarticle are being rotated.

9. The method of generating compound surface curvatures on an articlecomprising rotating said-article about a first axis and while inengagement with a rotating cup-like abrading tool, supporting saidabrading tool for tilting movement about a second fixed axis normal toand intersecting the axis of rotation of the article, and simultaneouslycontrolling said tilting movement and the rotation of said article aboutsaid first axis in such a manner that the said tool will assume a givenangle of tilt in one major meridian of said article and will assumeanother given angle of tilt in another major meridian of said article assaid tool and article are being rotated.

10. The method of generating compound surface curvatures on an articlecomprising rotating said article about a first axis andwhile inengagement with a rotating cup-like abrading tool, supporting saidabrading tool for tilting movement about a second fixed axis normal toand intersecting the axisof rotation of the article, simultaneouslycontrolling said tilting movement .and the rotation of said articleabout said first axis in such a manner that the said tool will assume agiven angle of tilt in one major meridian of said article and willassume another given angle of tilt in another major meridian of saidarticle as said tool and article are being rotated, andvarying theextent of the angle of tilt in said major meridians according to therelated curvatures desired.

11. The method of generating compound surface curvatures on an articlecomprising rotating said article about a first axis and while inengagement with a rotating cup-like abrading tool, supporting saidabrading tool for tilting movement about a second fixed axis normal toand interconnecting the axis of rotation of the article, simultaneouslycontrolling said tilting movement and the rotation of said article aboutsaid first axis in such a manner that the said tool will assume a givenangle of tilt in one major meridian of said article and will assumeanother given angle of tilt in another major meridian of said article assaid tool and article are being rotated, and causing said article andtool to move a controlled amount toward each other during said abrading.v

12. In a device of the character described the combination of'arotatable cupped abrading tool, means for supporting a lens blank forrotation about an axis passing through said blank, means for moving theblank and tool axially into engagement with, each other, and means forautomatically tilting said'tool and blank relative to each other todifferent given angular positions at given diiferent major meridians 01said blank, said tilting action occurring about a fixed axis normal toand intersecting said first axis, and said fixed axis traversing saidtool at a point laterally of the axis of rotation of said tool.

13. In a device of the character described the combination of arotatable cupped abrading tool,

. means for supporting a lens blank for rotation about an axis passingthrough said blank, means said fixed axis traversing the tool at a pointlaterally of the axis of rotation of said tool, and means forcontrolling the extent of movement of said tool and, lens blank towardeach other during said abrading.

14. In a device of the character described the combination of arotatable cupped abrading tool, means for supporting work for engagementwith the tool, said abrading tool being pivotally supported to be movedrelative to the work,'means for moving said tool on its pivot relativeto the work so as to simultaneously generate curves of two difierentradii one in each of the major meridians oi the work and meansfunctioning cooperatively with said last named means for cushioning themovement of the tool relative to the work.

15. In a device of the character described the combination of arotatable cupped abrading tool, means for supporting work for engagementwith the tool, said means being adjustable in a direction toward andaway from the tool, said abrading tool being pivotally supported to'bemoved relative to the work, means for moving said tool on its pivotrelative to the work so as to simultaneously generate curves of twodifierent radii one in each of the major meridians of the work and meansacting in opposition to said last named 7 relative to the work.

means for cushioning the movement of the tool CHARLES A. ELLIS. LAWRENCEA. SEVERY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 990,524 Chalmers et a1 Apr. 25,1911 1,901,181 McCabe Mar. 14, 1933 1,448,239 Schuessler Mar. 13, 19231,221,858 Hollands Apr. 10, 1917 881,168 Wall et a1. Mar. 10, 19081,332,074 Simpson Feb. 24, 1920 1,415,613 Simpson May 9, 1922 2,286,361Goddu June 16, 1942 1,003,816 Scoville Sept. 19, 1911 1,140,483 RogersMay 25, 1915 968,699 Schmidt Aug. 30, 1910 2,005,718 Desenberg June 25,1935 Re. 14,751 Brockbank Nov. 18, 1919 1,286,032 Lalsne Nov. 26, 19181,401,832 Taylor Dec. 27, 1921 2,352,146 Desenberg June 20, 1944

